1. Field
The following description relates to sensor communication service technologies, and more particularly, to methods and apparatuses for retransmitting a packet for sensor communications.
2. Description of the Related Art
A sensor network is a type of wireless network to transport sensing information generated by sensors to a final destination via wireless communications. Based on a low data transfer rate, as compared to mobile telecommunications network, the sensor network is generally operated on battery due to an environment difficult for supplying power in a wired manner.
In addition, as operated in a condition with a limited power, the sensor network has limited transmission wave intensity, resulting in forming of a short range of radio wave coverage. Thus, a low-power transmission mechanism is required for the sensor network to transmit data to a final destination.
Under such situations, IEEE802.15.4 has suggested guaranteed time slot (GTS) allocation and acknowledgement schemes, in which GTS ACK is operated, based on contentions, using CSMA-CA, during a Contention Access Period (CAP) and ACK for GTS transmission is carried out for each GTS, and thereby a probability of collisions is increased when using the CAP. As a result, ACK latency is caused, which leads to a latency delay in retransmission and increases the retransmission time. Further, a sensor device needs to stand by to receive ACKs independently transmitted by a coordinator during CAPs, thereby consuming a large amount of power.